1. Field of the Invention
This invention relates to surface modified resinous articles, and processes for making same, and more particularly, to an improved U.V. stabilizer composition for making said articles in a continuous manner.
2. Description of the Prior Art
In U.S. Pat. No. 4,770,905, issued 9/13/88, filed Dec. 23, 1986, there is described a method of incorporating a modifier ingredient, such as a UV stabilizer e.g. a solid benzophenone, into the surface region of a resinous body, such as a PVC sheet. The method includes the steps of: (1) immersing the body in a liquid, such as water, and (2) contacting the immersed body with a solution of the modifier ingredient in a solvent, such as methylene chloride, which is immiscible with the liquid and which will swell the surface of the resin to allow the solution to enter its surface region.
In the continuous mode of practicing this process, the solution is present as a lower layer, water is the upper layer, a continuous polymer sheet article is transported through the water, and the solution is pumped from the lower layer to the upper layer and directed onto the top surface of the sheet for a predetermined contact time during which the modifier ingredient is incorporated into the contacted surface. After the solution is applied, a jet of water is directed onto the treated surface to displace any residual, solution remaining thereon.
When this process is run for a extended period at room temperature, however, it is observed that a solid precipitate of the UV stabilizer material accumulates on the surface of the water layer. This solid material circulates through the system and tends to clog the pumping and piping equipment used both for applying the solution to the resin surface and for displacing residual solution thereon.
While suitable filters and/or skimmers may be used in the system to remove solid material floating on the surface of the water layer, such techniques require relatively costly equipment and periodic maintenance.
Accordingly, it is an object of the present invention to provide a U.V. stabilizer composition which will not deposit solid modifier material on the surface of the water layer in the resin surface modification process of the aforesaid patent application.